In color photography a dye image is formed during a process which includes the development of an imagewise exposed light-sensitive material comprising at least one silver halide emulsion layer and a dye forming coupler, followed by bleaching and fixing. During development, a color developing agent, usually a p-phenylenediamine, is oxidized in a reaction with silver halide, producing free silver. Oxidized developing agent then reacts with the coupler to form a dye whose color is determined by the chromophoric structure of the dye contributed by the coupler. Then, in the subsequent silver removing cycle, the developed silver is reoxidized by a bleaching agent and further fixed with a silver halide solubilizing agent for removal during the final wash cycle. An optional stabilizing treatment may be included prior to drying the so processed material.
The bleaching of the developed silver and the fixing of the silver halide for final removal from the element can be performed either in sequential steps using separate bleach and fix solutions or in one step using a single solution wherein the bleaching and fixing agents are combined. The latter solution is commonly referred to as a bleach-fix solution. Although a variety of oxidizing agents are known for use as silver bleaching agents in such bleach and bleach-fix solutions, metal complex salts of an organic acid, such as an EDTA-iron complex salt, have become a common bleaching agent because of their low toxicity and environmental safety. The use of such complexes in color photographic bleach and bleach-fix processing solutions is taught in, for example, U.S. Pat. Nos. 3,615,508; 3,770,437; 3,870,520; 4,242,442 and related art.
The use of such ferric complex salts as color photographic bleaching agents does, however, have certain disadvantages. One such disadvantage is the lower density of image dye derived from naphtholic and certain phenolic couplers in color photographic materials treated after color development in a solution containing such an organic complex salt as the bleaching agent. Although a variety of secondary conditions may contribute to an objectionably low density of image dye in any processed photographic material, it is the conversion of cyan image dye derived from naphtholic and certain phenolic couplers to a leuco compound which is generally recognized as the basic cause of the problem. Attempts made to overcome this problem have included a variety of approaches, such as modifying the bleach solution and/or the photographic element, treating the photographic element in a separate bath subsequent to the bleach step, or restricting the use of cyan dye-forming couplers to selected limited classes of compounds.
For example, U.S. Pat. Nos. 3,706,561; 3,770,437; 4,033,771; 4,301,236; 4,469,781 and 4,563,405 describe approaches which involve changing the concentration or composition of the bleach or bleach-fix solutions. U.S. Pat. No. 4,366,233 proposes to reduce the total amount of silver contained in layers disposed below the cyan dye-forming layer of a color photographic element. U.S. Pat. Nos. 3,820,997 and 4,469,781 and U.K. Pat. No. 1,393,335 relate to the treatment of the bleached photographic material with a variety of chemicals contained in a separate processing bath. U.S. Pat. Nos. 4,518,680; 4,374,922; and 4,591,548 disclose preferred classes of cyan dye-forming couplers for overcoming the above cited problem. The '548 patent also points to the presence of ferrous ions in the bleach solution as the cause for the conversion of cyan image dye to a leuco compound.
The art also recognizes that color photographic silver halide materials can contain acrylate and/or acrylic acid polymer latices for a variety of purposes. See U.S. Pat. Nos. 3,926,436; 4,201,589; 4,214,047; 4,247,627; 4,358,533; 4,612,278; German OLS 3,336,582; and Research Disclosure Item 19551, July 1980.
Also known in the art are polymeric couplers which contain acrylate repeating units as described in U.S. Pat. No. 4,612,278.
However, none of the art identified in the preceding paragraphs recognizes any connection between the problem of leuco dye formation and the presence of certain polymers, nor does it suggest the use of such polymers in conjunction with cyan couplers susceptible to leuco dye formation.